/*
 * Copyright © 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace Spring.Objects.Factory.Config;

/// <summary>
/// Holder for event handler values for an object.
/// </summary>
/// <author>Rick Evans (.NET)</author>
[Serializable]
public class EventValues
{
    /// <summary>
    /// The empty array of <see cref="Spring.Objects.IEventHandlerValue"/>s.
    /// </summary>
    private static readonly IEventHandlerValue[] EmptyHandlers = { };

    private static readonly string[] EmptyKeys = { };

    private Dictionary<string, List<IEventHandlerValue>> _eventHandlers;

    /// <summary>
    /// Creates a new instance of the
    /// <see cref="Spring.Objects.Factory.Config.EventValues"/> class.
    /// </summary>
    public EventValues()
    {
    }

    /// <summary>
    /// Creates a new instance of the
    /// <see cref="Spring.Objects.Factory.Config.EventValues"/> class.
    /// </summary>
    /// <param name="other">
    /// The <see cref="Spring.Objects.Factory.Config.EventValues"/>
    /// to be used to populate this instance.
    /// </param>
    public EventValues(EventValues other)
    {
        AddAll(other);
    }

    /// <summary>
    /// Gets the <see cref="System.Collections.ICollection"/> of events
    /// that have handlers associated with them.
    /// </summary>
    public ICollection<string> Events => (ICollection<string>) _eventHandlers?.Keys ?? EmptyKeys;

    /// <summary>
    /// Gets the <see cref="System.Collections.ICollection"/> of
    /// <see cref="Spring.Objects.IEventHandlerValue"/>s for the supplied
    /// event name.
    /// </summary>
    public ICollection<IEventHandlerValue> this[string eventName]
    {
        get
        {
            if (_eventHandlers == null || !_eventHandlers.TryGetValue(eventName, out var handlers))
            {
                return EmptyHandlers;
            }

            return handlers;
        }
    }

    /// <summary>
    /// Copy all given argument values into this object.
    /// </summary>
    /// <param name="other">
    /// The <see cref="Spring.Objects.Factory.Config.EventValues"/>
    /// to be used to populate this instance.
    /// </param>
    public void AddAll(EventValues other)
    {
        if (other?._eventHandlers != null)
        {
            foreach (var pair in other._eventHandlers)
            {
                var list = pair.Value;
                for (var i = 0; i < list.Count; i++)
                {
                    AddHandler(list[i]);
                }
            }
        }
    }

    /// <summary>
    /// Adds the supplied handler to the collection of event handlers.
    /// </summary>
    /// <param name="handler">The handler to be added.</param>
    public void AddHandler(IEventHandlerValue handler)
    {
        _eventHandlers = _eventHandlers ?? new Dictionary<string, List<IEventHandlerValue>>();

        if (!_eventHandlers.TryGetValue(handler.EventName, out var handlers))
        {
            handlers = new List<IEventHandlerValue>();
            _eventHandlers[handler.EventName] = handlers;
        }

        handlers.Add(handler);
    }
}
